Source:http://linkedlifedata.com/resource/umls/id/C0756081
NCI: A semi-synthetic derivative of pristinamycin, a natural occurring type B streptogramin. Quinupristin binds to the bacterial 50S ribosomal subunit, thereby inhibiting peptide chain elongation, and causing early termination of normal bacterial protein synthesis. Quinupristin is primarily effective against gram-positive cocci.